Hot runner injection nozzles are known. These nozzles are made of several parts designed to meet injection molding operating conditions for various materials and for various applications. These parts are made of various materials that need to be manufactured with high accuracy, low tolerances and also configured to be machine-able with available manufacturing equipment. These hot runner nozzles and the associated parts need to be designed and made to be easy to assemble and service in the field.
An area at the end of the nozzle is the nozzle tip area, which is proximate to the mold gate. In this area the injection pressure is very high. Nozzle tips are known and they are in many cases attached to the body of the nozzle in the nozzle tip area.
The nozzle tips sometimes have to be made of materials having conflicting properties or characteristics. If they are made of highly conductive materials, these materials are in many cases not very wear resistant. Many of the materials that can be used for the nozzle tips used in hot runner nozzles and that have good wear resistance have low thermal conductivity.
In many hot runner nozzle applications there is a need to use nozzle tip connectors, nozzle tip seals and nozzle tip insulators that have to cooperate with the nozzle tips and operate and perform together as a unit.
Because the nozzle tips and the tip seals are made of different materials and because they have a different thermal conductivity and a different coefficient of thermal expansion at the injection molding processing temperatures, there is always a concern with the known tips and seals regarding two types of leakage caused by the injection pressure of a molten material into a mold cavity through the nozzle tips. A first leakage, that sometimes is harder to contain, can appear between an outer surface of the tip and an inner surface of the tip seal. A second more common leakage can appear between an outer surface of the tip seal and a wall of a mold component adjacent the mold gate contacting the outer surface of the tip seal. Other leakage paths can further appear between other cooperating surfaces of the nozzle tip and tip seal that have small gaps caused by manufacturing errors or thermal expansion.
There is a need to design and manufacture hot runner nozzles and hot runner nozzle tips that have improved features and good thermal and wear resistance properties.
There is a need to design and manufacture nozzle tips, nozzle tip connectors, nozzle tip seals and nozzle tip insulators that have improved features and characteristics to better cooperate with the nozzle tips and better operate and better perform together as a unit.
There is a need to design and manufacture nozzle tips, nozzle tip connectors, nozzle tip seals and nozzle tip insulators where the first leakage and the second leakage are contained for long hours of operation of the hot runner nozzle.